1. Field of the Invention
The present invention relates to a novel class of amines and in particular to N-(polyoxyalkyl)-N-(alkyl)amines. These amines have utility in the preparation of polyurea and polyurethane/urea polymers which are useful in the preparation of elastomers and foams.
2. Prior Art
Current urethane technoloqy offers potential end users a versatility unsurpassed by any other polymeric system. Using readily available intermediates and processing equipment, it is possible to prepare essentially solid polyurethanes ranging from very soft (40 Shore A) elastomers to very hard (80 Shore D) plastics, and foamed polymers ranging from one to thirty pounds per cubic foot in density. These polyurethanes have generally very good physical properties and as a result large markets have evolved around their use.
Four major categories of intermediates are used in the preparation of most typical urethane systems. These include: polyols, isocyanates, chain extenders and additives (including blowing agents).
Several classes of polyols have been used in the preparation of urethane polymers. These include polyesters, polycaprolactones, poly(1,4-butylene)oxides and polyoxyalkylene oxides based on propylene and ethylene oxides. Of these, the latter have found greatest utility in the industry. Typically, polyols of this type are prepared by allowing propylene oxide (with or without ethylene oxide) to react with an "initiator molecule" such as glycerine under base catalyzed conditions. When ethylene oxide is used, it can be incorporated either as an internal block or random sequence in the polyol backbone or as a cap. Capping serves to convert a majority of the normal secondary hydroxyl groups on the polyol to more reactive primary hydroxyl groups.
For many applications, polyurethanes based on polyols such as those described above allow suitable processing latitude and reactivity with isocyanates and give urethane polymers with acceptable properties. However, there are more rigorous applications that require greater reactivity, better physical properties, or both. These include such applications as high performance reaction injection molding (RIM) systems and new rapid demold foams and elastomers.
A class of compounds with the potential to meet these more rigorous demands is taught in U.S. Pat. No. 3,654,370 and provides the basis for later patents to Texaco regarding the use of amine terminated polyethers in RIM. These materials are amine terminated polyethers where the hydroxyl group of a conventional polyol has been replaced with a primary amine group using the well known reaction of ammonia with alcohols polyols) under catalyzed high temperature conditions in the presence of hydrogen. This patent discloses certain secondary amine polyethers. However, since ammonia (and not an alkyl substituted amine) was exclusively used as the aminating agent, the secondary amine they generate must be limited to the secondary amine from intra molecular reactions which is discussed in the patent. These secondary amines are significantly different from those of the present invention, where the amination product forms directly from reaction of polyol and a substituted amine and not from reaction of an amine terminated polyol with itself.
These amines are extremely reactive with isocyanates, potentially increasing the overall reactivity of the system, and they generate highly stable urea groups which enhance the properties of the polymer, particularly at elevated temperatures. While the primary amine terminated polyethers have found some utility, their acceptance has been limited due largely to their very high reactivity.
In U.S. Pat. No. 2,629,740 the alkyl groups on the amine terminated polyethers are all functionalized with hydroxy groups.
In U.S. Pat. No. 3,660,319 the amine terminated polyethers described are tertiary amines. As a result they are not reactive toward isocyanates.
In U.S. Pat. No. 3,666,788 the alkyl groups on these amine terminated polyethers are all functionalized with cyano groups.
U.S. Pat. No. 3,373,204 discusses a monoalkyl amine terminated polyether identified as "polyoxypropylene 10 sorbitol". The molecular weight of these derivatives was limited to only 2350 (approximately a 383 equivalent weight).
U.S. Pat. No. 4,286,074 describes a 1000 equivalent weight (2000 molecular weight "MW") polypropylene oxide based diamine where the amines are substituted with isopropyl qroups. The isolated amine was not characterized and was made using a different process than set forth in the present invention. In fact the process used required the preexistence of a primary amine terminated 2000 MW material to be successful. No other examples of alkyl amine substituted materials are given, and no utility was demonstrated for this compound.
U.S. Pat. No. 4,417,075 describes di(secondary and tertiary alkyl aminoalkoxyl)alkanes where the equivalent weight is limited to about 400.
U.S. Pat. No. 4,588,840 describes aromatic amine terminated polyethers made from aniline and a polyol. No aliphatic amines are discussed.
U.S. Pat. No. 4,605,773 describes secondary amine containing polyethers which are monoaminoalcohols. No diamines are presented.
The reaction of a primary amine with an alcohol is a known approach. However, U.S. Pat. No. 4,686,242 teaches that this approach actually produces an amine terminated polyether where the amine qroups are predominantly primary amines.
French Pat. No. 1,466,708 describes secondary amines made from reaction of an epoxy terminated polyether with a primary amine. These reaction products produce alkanol amines rather than pure secondary amines.
West German Pat. No. 3,147,736 discusses polyurea articles manufactured from various amine containing polyethers. The amine polyethers exemplified are primary amine containing products. Certain secondary amine containing polyether are discussed (i.e. Fr. 1,466,708 above), which are in fact alkanol amines.